I'll go ahead and source this in case there's an issue, but Caitlin Doughty, in her book The Smoke Gets in Your Eyes, describes the drift toward "uniform" churchyard burials as a move to get closer to fragments of saints.

So we all know a little about how people would make pilgrimages to see or touch saints' remnants. Turns out being buried near them was supposed to be good, too. So folks would be buried as close as they could be, starting with rich people in the church itself and poor people in the ground outside.

It's supposed to be one of the first times a culture moved burial from the margin of town to its center, and it was to get close to the holy site of a saint's blessing.